1. Directional Elements – How Fast Can They Be?
Armando Guzmán, Venkat Mynam, Veselin Skendzic, and Jean León Eternod,
Schweitzer Engineering Laboratories, Inc.
Rafael Martínez Morales, Comisión Federal de Electricidad

2. Directional Elements
Are part of pilot protection schemes and can detect high-resistance faults when applied in permissive overreaching transfer trip (POTT) schemes
Add security to distance elements
Supervise overcurrent elements
Use time-domain incremental-quantity (TD32) and traveling-wave (TW32) elements to allow faster operation

3. Incremental Quantities Provide Fault Information

4. Replica Current D𝑖𝑧 Simplifies Pure Fault Network Representation
∆𝑣=− 𝑅 𝑆 ∆𝑖+ 𝐿 𝑆 𝑑∆𝑖 𝑑𝑡
∆𝑣=− 𝑍 𝑆 𝑅 𝑆 𝑍 𝑆 ∆𝑖+ 𝐿 𝑆 𝑍 𝑆 𝑑∆𝑖 𝑑𝑡
∆ 𝑖 𝑍 = 1 𝑍 𝑆 𝑅 𝑆 ∆𝑖+ 𝐿 𝑆 𝑑∆𝑖 𝑑𝑡
Replica current:
Even simpler equations…
∆𝑣=− 𝑍 𝑆 ∆ 𝑖 𝑍

5. Incremental Quantity Directional (TD32) Element
Reverse fault:
∆𝑣= 𝑍 𝐿 +𝑍 𝑅 ∆𝑖 𝑍
Forward fault:
∆𝑣=− 𝑍 𝑆 ∆𝑖 𝑍

6. Operating Quantity Torque Like in Electromechanical Relays
𝑇 𝑂𝑃 =−∆𝑣∙∆ 𝑖 𝑍

7. Operating and Restraining Quantities
𝑇 𝑂𝑃_𝐹𝑊𝐷 = 𝑍 𝑆 ∙ ∆ 𝑖 𝑍 2
𝑇 𝑅𝑇_𝐹𝑊𝐷 =𝑇𝐷32𝑍𝐹∙ ∆ 𝑖 𝑍 2
𝑇 𝑅𝑇_𝑅𝑉𝑆 =−𝑇𝐷32𝑍𝑅∙ ∆ 𝑖 𝑍 2
𝑇 𝑂𝑃_𝑅𝑉𝑆 =− 𝑍 𝐿 + 𝑍 𝑅 ∙ ∆ 𝑖 𝑍 2

8. Loop Incremental Quantities Provide Directional Decision
Voltage
Current AG
ΔvAG
ΔiZAG = ΔiAZ – Δi0Z

9. TD32 Directional Element Response to Forward CG Fault

10. TD32 Provides Speed With Security
Volts, Amps (Secondary)
VA, Secondary
Integrated VA

11. Birth of a Traveling Wave (TW) At Fault Location
408 kV
Voltage Collapse
vL – G t
GROUND

12. Birth of a TW At Instant of Voltage Collapse
408 kV TW front emanates in both directions on faulted conductor
Current waves are concurrently produced vF iF

13. TW Polarities as Seen by Relays Internal Fault (Forward Event)

14. TW Polarities as Seen by Relays External Fault

15. Use Differentiator Smoother Filter to Extract TW Signal
CG Fault on 400 kV, 224 km Line
Use Differentiator Smoother Filter to Extract TW Signal

16. Directional Decision Is Based On Integrated Torque
TW32 element chooses phase associated with maximum integrated torque and its reported direction

17. CTs Faithfully Reproduce High-Frequency Signals
Utilities have good experience with current TW-based fault-locating devices

18. CCVTs Provide First Wave Information
PROT415_TravelingWaveProtection_r2
CCVTs Provide First Wave Information

19. TW32 Design Accommodates CCVT Performance

20. Fast and Secure POTT Scheme
Local Terminal
TD32 provides dependability and security
Remote Terminal
TW32 provides speed

21. CFE 400 kV Network Relays on MID-TMD Line SPT Application

22. Performance of TD32 and TW32 Elements
Event Date
Terminal
Fault Type
TW32 Operating Time (ms)
TD32 Operating Time (ms)
Jan. 7, 2017
MID
Internal, AG
0.138
1.2
Jan. 15, 2017
TMD
External reverse, AG -
1.7
External forward, AG
1.9
Jan. 16, 2017
External reverse, CG
1.8
Mar. 28, 2017
Internal, CG
0.106
1.39
May 4, 2017
0.105
1.1
0.094
1.06
Aug. 23, 2017
Internal, AG, High Rf
8.75
7.8

23. Directional Element Response to Forward CG Fault

24. TD32 Element Operates in <2 ms
Integrated VA VA
TD32 Element Operates in <2 ms

25. TW32 Element Operates in <150 µs
PWRA
PWRB
PWRC VA
TW32 Element Operates in <150 µs

26. Performance of TD32 and TW32 Elements
Event Date
Terminal
Fault Type
TW32 Operating Time (ms)
TD32 Operating Time (ms)
Jan. 7, 2017
MID
Internal, AG
0.138
1.2
Jan. 15, 2017
TMD
External reverse, AG -
1.7
External forward, AG
1.9
Jan. 16, 2017
External reverse, CG
1.8
Mar. 28, 2017
Internal, CG
0.106
1.39
May 4, 2017
0.105
1.1
0.094
1.06
Aug. 23, 2017
Internal, AG, High Rf
8.75
7.8

27. Directional Element Response to Reverse AG Fault

28. TD32R Element Operates in <2 msVA
TD32R Element Operates in <2 ms
Integrated VA

29. CFE Field Evaluation POTT Scheme Based On TD32 and TW32 Elements
8 months, 9 fault records
TD32 operates reliably for all faults
Fastest operating time: 1.06 ms
Average operating time: 2.97 ms
TW32 detects 3 of 4 internal faults
Average operating time: 116 μs
Secure for all events and dependable for all faults (including high-resistance faults)

30. Questions?